Afew years ago, a mate of mine got stopped at a checkpoint for not wearing a helmet whilst riding a motorbike. He was told to join the queue, and he said "But why are there 2 queues?" The policeman replied "One is the 500 baht queue and the other is the 300 baht queue". He asked "What's the difference?" The policeman explained "If you join the 500 baht queue you will get a ticket which you have to take to the local police station. There you will have to wait for a couple of hours, and then you will pay your fine and get a receipt". My friend asked "What happens at the 300 baht queue?" He was told "You pay your 300 baht, do not get a receipt and you can go on your way". Needless to say, he chose the 300 baht queue which was substantially longer that the 500 baht queue!
P.S. This was not in Phuket, but another tourist destination!